OBSERVATORY

By Henry Fountain

Published: February 14, 2006

CORRECTION APPENDED

Volcano's Cold, Cold Shadow

The 1883 eruption of Krakatoa in Indonesia ranks among the most powerful volcanic blasts in history. It spewed six cubic miles of ash and dirt into the air and disrupted the world's climate for several years.

Krakatoa's reputation hardly needs burnishing, but Peter J. Gleckler of the Lawrence Livermore National Laboratory and his colleagues have done so anyway. They've found that the eruption had effects on ocean temperatures and sea level that persisted for decades.

The researchers analyzed 12 climate simulations, all covering the period from 1880 to 2000 but differing in other aspects, like the impact of greenhouse gases and the coupling effect between atmosphere and ocean. Half the models included the effects of volcanic eruptions; the other half did not.

The findings, published in the journal Nature, show that Krakatoa immediately lowered ocean surface temperatures, as gases and dust from the eruption reduced the amount of sunlight hitting the earth. But the simulations show that this cooling effect penetrated deeper in the ocean, creating zones of colder water at great depth that persisted for decades.

If Krakatoa had never exploded, the researchers found, the ocean warming and rise in sea level that occurred in the 20th century because of human activity would have been worse. The only 20th-century eruption on a similar scale, the 1991 Mount Pinatubo explosion in the Philippines, had less of a lasting effect. Ocean temperatures recovered faster because by then the warming trend was in full swing.

Keeping Up With an Eruption

It cannot hold a candle to Krakatoa, but Augustine, a volcano in the Cook Inlet, 170 miles southwest of Anchorage, has been erupting for the past month. And Augustine has something Krakatoa never had, monitoring over the Internet.

Amateur volcanologists can keep track of activity at the 4,100-foot-high volcano at the Alaskan Volcano Observatory site, www.avo.alaska.edu. The site has hourly text updates, Webcam views, seismic readings and other information.

Augustine has explosively erupted six times in the past two centuries, the last time in 1986. Since mid-January, it has been erupting sporadically, venting steam and ash. The biggest threat now is to aviation, because ash can damage jet engines.

Even Worms Use Potent Toxin

Among chemicals naturally found in animals, tetrodotoxin is special. TTX, as it is known, is a potent neurotoxin, and even in small amounts can cause respiratory paralysis and death.

TTX is what can make eating the Japanese delicacy fugu, or pufferfish, a dicey experience. Unless the fish is cleaned by an expert, the meal may be the diner's last.

Tetrodotoxin is found in many other creatures, too, including some frogs, newts and salamanders. In most cases, the toxin is thought to work as a defense against predators; it is often found in the skin, where it can ward off a hungry attacker.

But TTX has other uses, too. In the pufferfish, it functions as a pheromone to attract males to fertile females. And in a few organisms, most notably the blue-ringed octopus, TTX is used to capture prey.

Now researchers have found another creature that uses TTX offensively, a flatworm on the island of Guam.

Raphael Ritson-Williams of the Smithsonian Marine Station at Fort Pierce, Fla., and her colleagues conducted experiments with the flatworm, which is a previously unknown (and still undescribed) species.

They found that it rapidly killed and ate a number of different mollusks, including cowries. It even killed another flatworm. Dissection showed that the TTX was concentrated in the worm's feeding organ.

The team also tested to see whether TTX protected the flatworms from predators, offering the worms to fish on two reefs. Almost all were eaten, with no ill effects reported. The findings were published in The Proceedings of the National Academy of Sciences.

There's Nothing Like a Sympathetic Primate

During a pregnancy, it's not unusual for the spouse to share some of the symptoms. Men have been known to experience nausea, headache, backache and, perhaps most common, weight gain.

But humans aren't the only primates that can pack on the pounds when their mates are pregnant. A study of marmosets and cotton-top tamarins shows that males of these two squirrel-size monkey species gain weight, too.

Male marmosets and tamarins are known for being good parents, said the study's lead author, Toni E. Ziegler of the Wisconsin National Primate Research Center at the University of Wisconsin. They are among about 10 percent of primate species considered biparental, with both sexes sharing the work. Earlier studies had shown that males of both species underwent hormonal changes when their mates were pregnant. The hormones involved were associated with paternal infant care, and Dr. Ziegler and colleagues at the center wondered whether they might affect the animals' bodies. ''That's why I went looking for a weight change,'' Dr. Ziegler said.

The study, published in Biology Letters, showed that male marmosets weighed up to 20 percent more at the end of their mates' five-month pregnancy; marmosets without pregnant partners gained no weight. Male tamarins were up to 8 percent heavier at the end of their mates' six-month pregnancy.

In humans, sympathetic pregnancy symptoms are generally thought to be psychosomatic: emotions make a man raid the refrigerator. In the monkeys, however, Dr. Ziegler said, hormones are probably at work. ''If it is this hormone prolactin, which we suspect, it can actually change the metabolism of the monkey,'' she said. In the study, the animals didn't eat more than they normally did.

The hormonal changes are most likely set off when the male detects some chemical produced by the pregnant female, Dr. Ziegler said. ''We looked at their behavior very carefully,'' she added. ''We didn't really see that they started spending more time together or any other activity that would perk the male's hormones.'' Other studies will look at what the chemical cues might be.

Among their other parenting chores, the males of both species spend much time carrying their offspring around. The young monkeys (there are usually two in a litter) hang on to their father's hair, usually around the neck. It's hard work, Dr. Ziegler said, ''so they may be beefing up because they are going to be expending so much energy.''

Drawing (Drawing by Chris Gash)

Correction: February 18, 2006, Saturday
A brief report in the Observatory column of Science Times on Tuesday about the effects of the 1883 Krakatoa explosion on ocean temperatures referred incorrectly to another volcanic eruption, that of Mount Pinatubo in the Philippines in 1991. Pinatubo was not the only 20th-century eruption similar in scale to Krakatoa; Novarupta, an Alaskan volcano that erupted in 1912, was also comparable in size and intensity.